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Very interesting overall. I like this small factoid, "They can be made even smaller with lossy JPEG compression, but for optical navigation, precision counts; t
by geuis 12y ago
Very interesting overall. I like this small factoid, "They can be made even smaller with lossy JPEG compression, but for optical navigation, precision counts; the pictures have to be returned losslessly." I think this implies that the most distant JPEG software is currently in route to Pluto.
- mturmon 12y agoUse of lossy compression for science imagery is contentious. Because it's hard to characterize how the compression will affect as-yet-unseen science targets, it's hard to get scientists to accept lossy compression. You can sometimes get acceptance of prioritized downlink -- let automation decide what is most interesting, and downlink that first. Variations on that idea have been used for Mars rovers.
- simonh 12y agoI once visited a crackpot aliens-on-the-moon conspiracy website. They were showing zoomed-in images of lunar craters purporting to show regular, artificial-looking features indicating alien activity. Of course in context I'm sure you can guess what was going on. The images were heavily compressed jpegs and I soon realised the 'regular features' were compression artifacts. Still, it goes to show why some scientists don't like lossy compression. When you're looking at fine detail it's hard to be sure whether what you're seeing is 'real' or not.
- FeeTinesAMady 12y agoI don't think it implies that at all. I think they're saying that the pictures could be compressed with JPEG if they wanted them to be, but they very clearly state that they don't, and nothing in the article indicates that the spacecraft would have any other use for JPEG software.